Disease: a collection of symptoms that constitutes a recognizable medical problem or condition. Diseases are increasingly defined by such surrogate measures as blood pressure or bone density, which can paint an inexact picture of risk.

Guideline: a set of recommendations from a group of experts that lays out findings about a disease and how to treat it.

NIH: National Institutes of Health, the primary federal agency for conducting and supporting medical research. An arm of the Department of Health and Human Services, the NIH consists of 27 institutes and centers that focus on various diseases.

WHO: World Health Organization, an agency of the United Nations that coordinates global response to epidemics and provides a common language for disease used by doctors and health systems around the world. The WHO routinely invites experts to meetings where they reach consensus on various medical conditions and how they should be treated. Those findings are considered the most authoritative in the world and influence the global practice of medicine.